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Abstract #0681

"Purse String" Morphology of External Anal Sphincter in Nullipara Women with Ultrasound, High Resolution MRI, DTI and Fiber Tracking.

Shantanu Sinha1, Valmik Bhargava2, Melissa Ledgerwood2, Ravinder Mittal2

1Radiology, University of California at San Diego, San Diego, C, United States; 2Medicine, University of California at San Diego, San Diego, CA, United States

The External Anal Sphincter (EAS) is the most commonly affected muscle in patients with fecal incontinence. Current belief is that the EAS is donut shaped ; we hypothesize that the EAS instead has a purse-string morphology with transverse perinei being extensions of the EAS muscles. Such structure contracts in a circumferential manner to generate higher anal canal pressure than the circular shape and has significant relevance for the effects of lateral episiotomy on EAS function. We report a combination of multiple imaging techniques including 3D-ultrasound, structural MRI and fiber tractography that strongly suggest that EAS is configured as a purse-string.